There are several poisonous chemical pollutants in the environment, and these pollutants have different maximum allowable concentrations, e.g. benzene (5.1 ppb), Pb (50 ppb), Cd (5 ppb), paraquat (20 ppb), 1,1,1-trichloroethane (0.2 ppm). However, traditional detection instruments are expensive and take a lot of time for measurements, thereby limiting their time-effectiveness and popularity. Therefore, those skilled in the art are devoted to developing a highly sensitive, rapid, and low cost trace-detection device to analyze biological and chemical analytes.
A Raman Scattering Spectrum has the advantages of fingerprint specificity and multi-domain applications, and thus it is applied in trace detection. However, the Raman scattering intensity is very weak. Scientists use a metal structure to induce the surface-Enhanced Raman Scattering (SERS) to amplify the scattering intensity 104-1012 times.
However, when the analyte is put on the surface-enhanced Raman scattering substrate and then is dried, the reproducibility of the Raman scattering signal is bad due to the non-uniform distribution of the analyte. Therefore, the limit of detection (LOD) is quite limited.
Accordingly, there is a need to develop a SERS substrate. That will improve the reproducibility of the Raman scattering signal.